Isoprenoid compounds form a large ubiquitous class of natural products that fulfill a wide variety of essential cellular functions in al living organisms. In eukaryotes, isoprenoid compounds are synthesized by a mevalonate (MVA) dependent pathway. However, in many bacteria, these compounds are synthesized by an alternative, MVA-independent route whose first committed intermediate is 2-methylerythritol 4-phosphate (MEP). Both pathways converge at isopentenyl diphosphate (IPP) and subsequent steps are similar in all organisms. Since the N EP pathway is absent in mammals, it is considered an attractive target for the development of novel antibiotics. The pathogen, Bacillus anthracis belongs to the MEP pathway class of organisms. We will prepare a transgenic bacterial E. coli host cell whose genome contains disruptions in a first endogenous gene in the N4EP pathway and a second endogenous gene which is located downstream of the first gene in the M P pathway. A transgene from B. anthracis that functionally replaces the disrupted downstream gene will be cloned into the cell. The growth of the host cell in the presence of test agent is then compared to a control culture to determine the activity of the test agent. Where the test agent renders the bacterial host cell inviable on media containing a chemical supplement to relieve the DXP block and viable on the media containing NIVA indicates that the test agent has the potential to be an effective antibacterial against B. anthracis.